when using an SMTP Server that requires authentication, you need to use the Pear Mail for SMTP mail object.
open the server behaviors panel (Window -> Server Behaviors). In the server behaviors list, double click the Universal Email server behavior.
in the UE server behavior, click the envelope icon to get to the email server settings.
For the mail object, select to sue the Pear Mail for SMTP object, you can then specify your username and password to connect to the SMTP server.